apache/hadoop · error · HadoopIllegalArgumentException

XAttr name cannot be empty.

Error message

XAttr name cannot be empty.

What it means

buildXAttr rejects names whose namespace prefix parses but whose attribute part is empty: when the first '.' is the last character of the string (prefixIndex == name.length() - 1), the remainder after the dot is the empty string, so the call fails fast with HadoopIllegalArgumentException ('XAttr name cannot be empty.').

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/XAttrHelper.java:57

  public static XAttr buildXAttr(String name) {
    return buildXAttr(name, null);
  }

  /**
   * Build <code>XAttr</code> from name with prefix and value.
   * Name can not be null. Value can be null. The name and prefix
   * are validated.
   * Both name and namespace are case sensitive.
   */
  public static XAttr buildXAttr(String name, byte[] value) {
    Preconditions.checkNotNull(name, "XAttr name cannot be null.");

    final int prefixIndex = name.indexOf(".");
    if (prefixIndex < 3) {// Prefix length is at least 3.
      throw new HadoopIllegalArgumentException("An XAttr name must be " +
          "prefixed with user/trusted/security/system/raw, followed by a '.'");
    } else if (prefixIndex == name.length() - 1) {
      throw new HadoopIllegalArgumentException("XAttr name cannot be empty.");
    }

    NameSpace ns;
    final String prefix = name.substring(0, prefixIndex);
    if (StringUtils.equalsIgnoreCase(prefix, NameSpace.USER.toString())) {
      ns = NameSpace.USER;
    } else if (
        StringUtils.equalsIgnoreCase(prefix, NameSpace.TRUSTED.toString())) {
      ns = NameSpace.TRUSTED;
    } else if (
        StringUtils.equalsIgnoreCase(prefix, NameSpace.SYSTEM.toString())) {
      ns = NameSpace.SYSTEM;
    } else if (
        StringUtils.equalsIgnoreCase(prefix, NameSpace.SECURITY.toString())) {
      ns = NameSpace.SECURITY;
    } else if (
        StringUtils.equalsIgnoreCase(prefix, NameSpace.RAW.toString())) {
      ns = NameSpace.RAW;

View on GitHub (pinned to 2add963021)

Solutions

1. Supply a non-empty attribute name after the namespace dot, e.g. 'user.color'.
2. Check suffix variables for null/empty before assembling the name.
3. Validate with a regex that requires at least one character after the dot.

Example fix

// before
String name = "user." + attrSuffix; // attrSuffix == ""
dfs.setXAttr(path, name, value);

// after
Preconditions.checkArgument(!attrSuffix.isEmpty(), "attr suffix required");
dfs.setXAttr(path, "user." + attrSuffix, value);

if (name == null || name.isEmpty()
    || name.charAt(name.length() - 1) == '.') {
  throw new IllegalArgumentException(
      "xattr name must have a non-empty part after '<namespace>.': " + name);
}

try {
  dfs.setXAttr(path, name, value);
} catch (HadoopIllegalArgumentException e) {
  if (e.getMessage() != null && e.getMessage().contains("cannot be empty")) {
    // empty attribute suffix: fix the caller's input assembly
    throw new IllegalArgumentException("Empty xattr suffix in '" + name + "'", e);
  }
  throw e;
}

When it happens

Trigger: setXAttr/removeXAttr/getXAttrs with a name like 'user.' or 'raw.' — a trailing dot with nothing after it.

Common situations: String concatenation where the suffix variable is empty ('user.' + attr with attr == ""); templating that renders a bare namespace; input trimmed so it ends at the dot; dynamic name lists containing one malformed entry.

Related errors

• An XAttr name must be prefixed with user/trusted/security/sy
• XAttr names can not be null or empty.
• Path part {s} from URI {p} is not a valid filename.
• {} doesn't support setXAttr
• {} doesn't support getXAttr

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/4cfc4605c2582444. Report an issue: GitHub.